Ive read many topics, many times regarding the small or large setting on hometheater amps and what I usually read is set them to small so they dont get damaged.

Thing is I have newly acquired B&W 705's (damn break in will yer) with a sub connected on the high level lead so in effect they are full range...so my first question is I can I safetly set them to large without fear of damage?

Second is that on my yamaha 2500 should I set the bass out to Both or just Sub?

Silly question and yes I know I should already know the answers and I kinda do but its quite in here lately :-)

If you set it to both, then the front speakers will get the LFE channel as well as the regular full frequency signal. This is good in that it helps the subwoofer integrate better with the sound coming from your fronts, i.e. not sounding like a box in your corner. As far as setting your speakers to large or small, I for the most part, defer to the large setting, because most good speakers are designed to run at full range anyway, only the relatively new construct of sub-sat systems are restricted to the small setting. If it makes you nervous doing so, you could always run the YPAO on the Yamaha and go with the speaker size setting it recommends, although it will most likely set them to small(it does for about 90% of speakers; I believe this is because of the THX Select aspect of the amp. THX specs the crossover point for your mains and your sub to always be at 80hz.

Hi Hoop,

YPAO sets it to large. Even with the subs high level removed. I have gone with what it suggests and yes definately agree it integrates better when set to both.

Thanks for replying

Tony Grimani says set all speakers to small and send everything below 80Hz to the sub. Most speakers will play below 80, but if randomly placing subs in the room (basically what you're doing when allowing low frequencies to go to the main speakers) you run the risk of having some bad cancellations.

You won't damage your 705s by sending full range to them. I would set them to small, hook up the sub to the LFE Preout of the Yamaha, and set the receiver to send the bass to just the sub. If you can only hook the sub up to speaker level outs, then tell the receiver you have no sub and set the front left and right to large.

Listen both ways and see what happens in your room, then pick the one you like best.

Matt

This is what i would reccommend.

Hi all, I have both high level and low line connected to an MJ acoustics sub. When I do a frequency sweep L&R using AVIA it goes all the way down to 20. Seems a shame to cut it off at 80 though I originally bought the high level lead to go on the center but sold my speakers to buy the 705's so now it goes on the fronts.

I'll play around and see whats best after a week or two.

Matt thanks for positng Tony Grimani's opinion.

A nice blast of movies yesterday has loosened the speakers, i was cringing everytime some one spoke or when some high frequency hit....I was almost begining to think they were busted as it was so shrilly

cant say id do that

Hi, oex, That how its designed to work. Why wouldnt you do it?

Really? I guess it was an assumption of mine that you would hook up the sub to the line output if you had one, or to the speaker output if you did not have a line out.* I can't remember looking at any instruction books to see if they mention connecting both.

*You also would want to use the speaker output if the sub has a high-level crossover and you use satellites designed to be hooked up through that crossover, or if you use the Speaker B output...it is really weird to turn on Speaker B in one room, turn off Speaker A in the main room, and have the sub thumping away in the main room all by itself because it is connected through the line output.



Why? This cutoff defines the HIGHEST frequency that the sub will get from the receiver, not the lowest. If it can go down to 20, it will do that no matter what the cutoff is set to. The cutoff determines how the system makes the transition between low bass to the sub and midbass to the mains.

You can't get a good result with the mains to Small and connect the sub to the speaker outputs, because no bass will go to the speaker outputs.

Hi Ernie,

Without the sub connected the sweep would end at 42 as thats where the 705's end. By connecting the sub via the high level lead it extends the range down to 20 when speakers set to large.

heres are instructions for setting subs via both high level and low level

Can I connect both the high & low level inputs simultaneously?
Yes you can connect both the high & low level inputs simultaneously. This question is asked by many music lovers who have the high level cable connection for music and want the added benefit from their sub with movies through the low level connection and movie buffs who respectively wish to use their sub for music. With respect to movies, connecting both the high & low level inputs simultaneously, starts to benefit when there is little or no LFE signal being sent to the sub from a dedicated sub out on an AV amp. Having the high level cable connected from the main or centre (recommended) speaker outs on an amp or wired off the back of the speakers, adds a full range signal into the high level input of your sub. Cleverly blended together using the independent volume controls, both the high and low level signals can give you the ultimate in depth reproduction throughout the entire movie, as well as exploding, thumping LFE (low frequency effects) bundled into one subwoofer for the ultimate listening pleasure. http://www.mjacoustics.co.uk/

Q13. Can high and low level inputs be used simultaneously?
A13. Yes, all Rel sub bass systems are designed to use high and low level inputs simultaneously if required. Both high and low inputs have independent gain controls.[Link: rel.net]

Which model? PLEASE ALWAYS MENTION THE MODEL NUMBER. For the reason, please read on....



John,
I don't think so. Your model might indeed be designed to work that way, but you are making a total ASSumption here. I think this issue should be decided on a model by model basis, starting with the assumption that you CAN'T hook them up at the same time, with a thorough reading of the manual for indications that you can.

Your comment looked so unusual that I did some research.

From the MJ Acoustics web site:
"MJ Acoustics Reference 100, 150 Reference I Mk II, Pro 100, Pro 500, Pro 1650 : High & Low level simultaneous connection capable."

These are indeed designed to be connected both ways at the same time. Color me surprised!

"MJ Acoustics Pro 50: Speaker and line level inputs with Gain Control Range 80dB."

Nothing on the web site goes further than this to say whether they are or are not designed to be connected at the same time. I would infer that they are not, since the first models I mention specifically state that they are, this one does not, it is in the same series as the Pro 100 and Pro 500, and being less expensive it might not have features that the others have.

"MJ Acoustics Reference 200: 'Hi' Control: This function parameter setting allows adjustment of the gain from the inputs received via, either the Neutrik Speakon or RCA line level connectors. This parameter enables adjustment of gain and thus sound pressure output produced in relation to the input from sources connected to these inputs."

Notice that nothing there specifically says you can or cannot connect both at the same time. It does, however, say "via EITHER the Neutrik Speakon OR…" which could imply that both are not appropriate.

From other web sites:

Velodyne HGS-12x
"Your new subwoofer is equipped with line-level inputs. Use the LINE-LEVEL jacks when connecting your subwoofer to a preamp, signal processor, line-level crossover, or receiver with preamp-level outputs. If your receiver/electronics does not have RCA type line level outputs, you must use a high to low level adapter. Consult the dealer where you purchased the unit for further details."
Not both with this model!


Phase Technology
"There are two ways to add Phase Technology Powered Subwoofers to your system: low-level and high-level connections. These methods differ depending on whether you are using components or a multi-purpose receiver; whether your amplifier, receiver or surround-sound decoder have separate subwoofer-output connections; and whether you are using one or two subwoofers in your system.
Therefore, please read the following guidelines carefully. Be sure to choose one or the other connection options as using both at the same time could severely damage your speakers and amplifier. And always remember to keep the polarity connections correct (positive to positive and negative to negative)."
NOT BOTH THERE WITH PREJUDICE.

Both Mirage and DEf tech are EMPHATIC about not using both

Hi Ernie,

Me thinks I shall email the makers and see if they will pop along and answer these questions.

I have a reference 100. I am under the impression all their subs can be connected both inputs same time.

Hopefully they will pop along to answer these questions or maybe provide me some via email.

Lets see what tomorrow brings :-)

Some comments on this MJ weird setup stuff.


This is where it gets interesting. They are assuming that you can't have a different setup that will work. AND, they are preying on the fragile minds of audiophiles. Kinda funny, really.


See, this is the point. They are assuming that you will set front speakers to large. Ok. And that can mean that you will have no sub when you listen to stereo music. But there is an easy alternative in most receivers. Set the receiver to Sub On & Front Large, however it says to do so. This should send all your low frequencies below the crossover (probably 80Hz) to both the fronts and the sub.

Another possiblity is to simply set your fronts to large, sub to off, and wire the sub with the front line-level outputs instead of the sub output. Calibration of the bass frequencies is trickier with either of these choices, but it can have a superior result.

Either way, you don't have to plug in the speaker wires and strain your amp. Isn't this sub matched properly to its internal amp so that amp gives the best result?


This must be an interesting feat of engineering. I'm no speaker designer, but isn't it pretty tricky to have 2 amps pushing the same speaker? I guess if it's ok, great. But it sure seems complex for an issue that has other, far easier solutions.

This message was edited by Spiky on 05/15/05 20:43 ET.

Spiky,

Wouldn't be 2 amps pushing the same speaker would it? Wouldn't it just be 2 line level signals being combined and amplified by the Sub's amp? If that is the case, it may be noisy and distorted, but not dangerous to the speaker. Am I right, or am I lost?

Mark